Fan runs fine in test mode, FF thermistor ohms out good, no ice built up, door switches good. Fan turns on for a few seconds then stops. Customer says it won't come back on. Anyone else having this problem? I'm thinking a new board.

What is the frost pattern like? Is there a thermistor attached to the harness for the fan? Most evap fan in these type of units are thermistor controlled. Rather than a new board I would look at evap motor or thermistor. If I remember correctly in test mode it bypasses thermistors and directly powers fan. Therefore you have a temperature read issue on the fan. If the frost pattern and temperatures are good in unit it must be moving air to create the proper temp.

You can also test the evap fan by having the door open and push in switch. Fan should actuate unless there is a magnetic control. You can use a magnetic to fool it into thinking it is closed in some cases.

Frost pattern was fine and everything in the freezer is nice and frozen solid. Yeah, I stood there with a magnet on the switch and the lights went off but no fan. I'll check to see if there's a thermistor on the fan.